The experiments described in this application are designed to provide important data regarding fundamental aspects of the cell biology and extra-cellular matrix of meniscal fibrocartilage. The specific aims of the project are: (1) To develop a serum-free, defined medium for the cell culture of rabbit meniscal fibrochondrocytes to facilitate further in vitro studies, (2) To determine if, as suggested by preliminary studies, fibrochondrocytes utilize a specific and distinct attachment protein other than fibronectin and chondronectin, (3) To study the ability of rabbit meniscal fibrochondrocytes to divide and synthesize extracellular matrix in response to injury in organ culture, and (4) To determine the effect of purified growth factors on the reparative process in #3 above. To achieve these goals the following methodology will be used: (1) Cell and organ culture techniques, (2) Histological techniques to include light and electron microscopy, (3) Conventional liquid chromatography, (4) High-performance liquid chromatography and (5) SDS-polyacrylamide gel electrophoresis. The data obtained from the proposed experiments will provide a basis for future studies to include (1) the effects of estrogens and anti-estrogens on the metabolism of fibrochondrocytes, (2) determination of the role of attachment factors in the differentiation and development of fibrocartilage as well as binding interactions with other matrix constituents and (3) design of an animal model to study meniscal repair and regeneration in vivo. Insights gained from the animal model can be expected to further our understanding of the problems of human meniscal repair and thereby aid in design and selection of treatment modalities.